20-DatalogResolution

• Notes
• 11

This preview shows page 4 - 8 out of 11 pages.

236 Datalog: #-comments and #|…|#-comments Queries Prolog: | ?- is the interactive prompt, so | ?- p(Y). is the query 236 Datalog: not interactive, no prompt, just P(Y)?

Subscribe to view the full document.

Discussion #20 Chapter 4, Sections 4.1 & 4.4.1-3 5/11 236 Datalog Prolog (Similarities…) Same syntax for Facts and Rules Comma means No semicolon for ( ) use 2 rules. parent(x,y) :- mother(x,y); father(x,y). changes to: parent(x,y) :- mother(x,y). parent(x,y) :- father(x,y). Recursive rules the same Derivations the same Instantiation Unification Resolution (derivations of empty clause) Backtracking Results same: “can be derived from database”
Discussion #20 Chapter 4, Sections 4.1 & 4.4.1-3 6/11 Prolog Derivations Although derivations are the same, there is a different way of looking at the derivation in terms of Goals query and atomic formulas in the body of the rule. Success can be derived Failure cannot be derived We can use this same view in 236 Datalog. We’ll use the following database to explain these ideas. Facts: sister('ann','bob'). parent('bob','jay'). parent('bob','kay'). Rules: aunt(x,y) :- sister(x,z), parent(z,y). Queries: aunt('ann','jay')? aunt('ann',x)?

Subscribe to view the full document.

Discussion #20 Chapter 4, Sections 4.1 & 4.4.1-3 7/11 Resolution 1. ¬ aunt('ann', 'jay' ) 2. aunt( 'ann' , 'jay' ) :- sister( 'ann' ,z), parent(z, 'jay' ).
You've reached the end of this preview.
• Winter '12
• MichaelGoodrich
• Recursion, Backtracking, Lower case, Query language, Datalog

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern